Scanning mechanism for film developer, and the like

ABSTRACT

A light scanning mechanism for use in conjunction with automatic X-ray film developing apparatus, and the like. The mechanism permits a red beam to be repeatedly scanned across the film being developed in order to provide appropriate control signals so that the developing process may be stopped automatically when a desired density has been reached. The scanning mechanism includes a resilient member, such as a leaf spring, which couples the source of the red beam of light to a motor drive shaft. The motor is intermittently energized to cause the red beam to be cyclically moved in a random spiral scanning path.

United States Patent [1 1 Gregg SCANNING MECHANISM FOR FILM DEVELOPER, AND THE LIKE Inventor: David Paul Gre g, 1936 Kelton Ave., Los Angeles, Calif. 90025 Filed: Dec. 14, 1972 Appl. No.: 315,073

us. Cl. 240/101, 95/89 R F2lp 3/06, 603d 3/10 Field of Search 95/89 R, 94 R;.

[56] References Cited UNITED STATES PATENTS 2,210,718 8/1940 Hennin ger 'et a1. 240/10.l 3,531,636 I 9/1970 Birch 24 0/lO.1 1,959,233 5/1934 Franke 95/89 R? Power Source /ecfr/a J/a far 54 7a Jar/":8 a/ Payer far b ag/fault! Jan. 1, 1974 Primary ExaminerFred L. Braun Attorney-Keith D. Beecher 5 7 ABSTRACT ning mechanism includes a resilient member, such as a 7 leaf spring, which couples the source of the red beam of light to a motor drive shaft. The motor is intermitten tly energized to cause the red beam to be cyclically moved in a random spiral scanning path.

4 Claims, 1 Drawing Figure I PATENIEBJAN 11914 SM R SCANNING MECHANISM FOR FILM DEVELOPER, AND THE LIKE BACKGROUND OF THE INVENTION The scanning mechanism of the invention has particular utility in automatic film processing apparatus such as described in Copending application Ser. No. 214,924, filed Jan. 3, 1972, now abandoned. The apparatus described in the copending application is capable of causing film to be developed with a desired density and, within certain limitations, regardless of whether the film has been over-exposed or under-exposed, regardless of the temperature of the developing bath, and regardless of the depletion of the developing solution.

The apparatus of the-copending application includes a control system which responds to the scanning of the exposed film in a developing solution by a red beam to cause the developing process to be terminated when a I desired contrast is achieved. The red beam is derived, for example, from a laser, or other appropriate source of red light, and by subsequently transforming into electrical signals the radiant energy passing through the film and through the developer solution.

In the mechanism of the present invention, the desired scanning action of the red beam is derived, as will be described, by a simple resilient coupling between the source and a motor drive shaft.

As pointed out in the copending application, a major problem in developing photographic film is the establishment of a developing time which will permit a satisfactory density to be achieved, even though the film may have been over-exposed or under-exposed, even though the temperature of the developing solution may vary, or even when the depletion of the developing solution is unknown. This problem of achieving satisfactory density in X-ray films is especially prevalent in hospitals, clinics and dental offices, and it results in the technician or doctor s either having to interpret from less than satisfactory results, or having to perform expensive and time consuming re-takes.

The system and apparatus described in the copending application utilizes a red beam as a basis for controlling the time in which the exposed .X-ray film is actually submerged in the developing solution. Since the X-ray film is relatively inesensitive to radiant energy in the red portion of the spectrum, there is little tendency for it to be fogged by the red beam.

BRIEF DESCRIPTION OF THE DRAWING DETAILED DESCRIPTION OF THE ILLUSTRATED;

EMBODIMENT The apparatus illustrated in FIG. 1 includes a trans- 2 ode, a heliumneon laser, or other known type of red light source. The red light source may be of continuous wave type or pulsed, for example, at a rate of times a second by a suitable pulsing circuit to prevent excessive heating. The red light pulse width may, for example, be of the order of 200 microseconds, although any appropriate parameters may be used.

In the practice of the present invention, the source 16 is mounted on a resilient member such as a leaf spring 50 which, in turn, is mounted on the shaft 52 of an electric drive motor 54. Slip rings 57 on the motor shaft, in combination with stationary brushes 58 conduct the necessary power from an appropriate electrical source of power to energize the laser. Flexible leads connect the slip rings to the input terminals of the red light source 16. A small eccentric weight 60 is fastened to one side of the resilient housing of the laser. The drive motor 54 may, for example, be an induction type, and it is driven from an appropriate alternating current power source through a power interrupter circuit 56. The power interrupter circuit periodically interrupts the power to the motor 54 so that it is intermittently energized.

It will vbe appreciated that each time the electric motor is energized, the resulting acceleration of the drive shaft 52 will cause the leaf spring 50 to bend increasingly under the effect of the unbalanced mass of I the eccentric weight 60, so that the red point source 16 is driven along a conically spiral path with respect to the axis of rotation of the motor shaft 52. This causes the red beam from the red light source 16 to be scanned spirally across the film 12 within the transparent tank 10. The spiral scanning occurs in a manner such that the area of the film 12 is sampled to a large I degree. When the spiral scan has increased to a radius equal to the outermost portion of the film in the tank, the power to the motor 54 is interrupted and a braking force is applied, giving a rate of deceleration equal to that of the previous acceleration. Therefore, the compliance of the leaf spring 50, in combination with the decreasing rotational speed of the weighted laser housing, 16 and 58, causes the spinning red light source 16 to describe an ever smaller radius and hence a contracting conical spiral scan, which randomly samples once again the area of the film 12.

The spiraling scanning red beam, after it has passed through the transparent tank 10, through the solution in the tank 10 and through the film 12, is reflected from a reflector and is detected by a red energy detector and electric transducer 30 at the focus. The scanning beam may be reflected to the detector from all its scanning positions by means, for example, of a prolate semiellipsoidal reflector 32. The reflector 32 is positioned on the opposite side of the tank 10 from the scanning beam from the red source 16, as shown. The reflector may be replaced, for example, by a convex lens, a Fresnel lens, a Zone plate, or other appropriate optical equipment. The red detector 30 may, for example, be a silicon photo diode, or any other appropriate red light sensor may be used.

The electrical output from the red energy detector 30 is applied to an electronic processing circuit designated 34, which is described in detail in the aforesaid copending application. The output from the processing circuit 34, may, for example, be used to activate any appropriate indicator orcontrol circuit, as fully described in the copending application.

The invention provides, therefore, a simple and expeditious mechanical scanner which has a multiplicity of uses, and which finds particular use in an automatic film developing system. It will be appreciated that while a particular embodiment of the invention has been shown and described, modifications may be made. It is intended in the following claims to cover all modifications which come within the spirit and scope of the invention.

What is claimed is:

1. A scanning mechanism for a photographic film developing apparatus, or the like, comprising: a drive motor having a drive shaft; a bendable resilient member having one end mounted on said drive shaft; and weight means including a radiation source mounted on the other end of said resilient member in position to causevsaid resilient member to bend increasingly upon acceleration of said drive shaft and to bend decreasingly upon deceleration of said drive shaft, said radiation source being displaced radially of the axis of rotation of said drive shaft by increasing amounts as said drive shaft rotates at accelerated speeds and by decreasing amounts as said drive shaft rotates at decelerated speeds so that said source is driven along a conical path.

2. The scanning mechanism defined in claim 1, in which said resilient member is configured as a leaf spring.

3. The scanning mechanism defined in claim 1, in which said radiation source is a red light source.

4. A scanning mechanism as defined in claim 1, and which includes a power interrupter circuit connected to said motor for periodically interrupting the power to the motor for causing cyclic variations in the speed of the motor. 

1. A scanning mechanism for a photographic film developing apparatus, or the like, comprising: a drive motor having a drive shaft; a bendable resilient member having one end mounted on said drive shaft; and weight means including a radiation source mounted on the other end of said resilient member in position to cause said resilient member to bend increasingly upon acceleration of said drive shaft and to bend decreasingly upon deceleration of said drive shaft, said radiation source being displaced radially of the axis of rotation of said drive shaft by increasing amounts as said drive shaft rotates at accelerated speeds and by decreasing amounts as said drive shaft rotates at decelerated speeds so that said source is driven along a conical path.
 2. The scanning mechanism defined in claim 1, in which said resilient member is configured as a leaf spring.
 3. The scanning mechanism defined in claim 1, in which said radiation source is a red light source.
 4. A scanning mechanism as defined in claim 1, and which includes a power interrupter circuit connected to said motor for periodically interrupting the power to the motor for causing cyclic variations in the speed of the motor. 